The present invention relates to a device for improving the performance and thereby increasing the applicability of single pass, vision guided, robot-controlled welding systems. The device can also improve vision system performance in other manufacturing environments.
Present robot-controlled welding systems require stringent robot and workpiece position accuracies for acceptable weld seams. Vision systems have been added to these robots which can locate the seams in three dimensional space and correct the robot position to achieve the desired position and orientation of the robot-mounted weld torch with respect to the workpiece seam. This reduces the workpiece and robot position accuracy requirements. Two alternative welding schemes are possible. They are two pass and single pass welding.
Two pass welding separates the operation into two passes along the weld seam. During the first pass the robot moves along the weld seam allowing the vision system to view the seam and generate the seam location in three dimensional space. This seam location information is used to modify the robot path during a second pass, when the welding is done, so that the weld tip is positioned as desired with respect to the seam. This method requires two passes along the seam, thereby increasing the cycle time.
Single pass welding systems combine the vision and welding operation into one pass along the weld seam. The vision system looks at the same time welding occurs and continuously updates the robot to achieve the desired weld tip location and orientation with respect to the seam. The vision system looks slightly in front of the weld area to determine seam position prior to the weld tip reaching the viewed seam location.
There are several significant problems associated with single pass welding which interfere with the vision system including direct arc glare, reflected arc glare, weld spatter and weld fumes. These items are seen by the vision system and can prevent seam data from being generated or cause the vision system to generate wrong data. Extensive hardware and/or software processing of this vision data is required to locate the seam in the presence of these interfering factors during single pass welding.